1. Field of the Invention
The present invention relates to compressed air systems used in heavy vehicle braking systems. More particularly, this invention is directed to an air brake compressor system having a discharge oil filter disposed adjacent a heat generating element.
2. Discussion of the Art
Compressed air systems are used in brake systems to provide and maintain air under pressure to operate vehicle brakes and any auxiliary air systems. Conventional compressed air systems include an air compressor for generating pressurized air and a drying device disposed downstream from the air compressor for drying the air. A typical dryer includes a desiccant material enclosed within a housing which removes water from the compressed air.
Most air brake compressors are supplied with oil from the vehicle engine in order to lubricate the bearings and other components of the compressor. However, because oil is difficult to contain, it passes into the pressurized air stream exiting the compressor. Conventional air brake systems are designed such that the compressed air exiting from the air compressor is directly introduced into the air dryer. By doing so, the desiccant housed within the air dryer often becomes contaminated with the oil accompanying the air delivered from the compressor.
In order to minimize contamination of the air dryer desiccant, attempts have been made to place a filtering element at or adjacent the inlet area of the air dryer. The filtering element or oil filter would effectively remove oil from the compressed air before reaching the desiccant material. However, when the compressed air reaches the air dryer, much of the water vapor and oil will have condensed to form emulsions having a consistency similar to mayonnaise. The condensed oil and water emulsions are high in viscosity, difficult to filter, and require frequent filter changes.
In addition, the filter must be equipped with a drain passage or system to dispose of the filtered material. A relatively large draining capacity is required since a considerable amount of the water vapor condenses to liquid water upon reaching the air dryer. This, unfortunately adds to the complexity and cost of the compressed air system. Furthermore, water resulting from the condensed vapor has the potential to freeze. In order to prevent both freezing and the water vapor from condensing to form emulsions, heaters have been incorporated into filter devices to maintain the water in liquid form. However, the addition of a heating element adds to the complexity and cost of the compressed air system.
Accordingly, a continued need exists in the art to effectively eliminate desiccant contamination in an air dryer assembly of a brake system without having to use a complex drainage system or a separate heating element.
The present invention provides a compressed air system for pneumatic brake systems that meets the above needs and others in a simple and economical manner.
More particularly, the invention provides a compressed air system for an air brake system having a heat generating element operating at an elevated temperature to maintain water in a vapor form. A discharge oil filter is disposed downstream from the heat generating element for filtering oil from a stream of compressed air. The discharge oil filter is positioned sufficiently close to the heat generating element to maintain water in the compressed air stream in a vapor state while passing through the discharge oil filter. An air dryer disposed downstream from the discharge oil filter removes water from the stream of compressed air after the water vapor has condensed.
In a preferred embodiment, the heat generating element is an air brake compressor.
According to another proposed embodiment, a compressed air system for an air brake system includes a separate heat generating element operating at an elevated temperature to maintain water in a vapor state. Again, a discharge oil filter disposed downstream from the heat generating element removes oil from the compressed air. The discharge oil filter has an oil removal media formulated to agglomerate oil accompanying the stream of compressed air. The agglomerated oil is entrained in the compressed air and removed downstream from the discharge oil filter. A downstream air dryer subsequently removes water from the compressed air stream.
Preferably, the discharge oil filter is positioned adjacent the heat generating element to maintain water in a vapor state while the compressed air is filtered by the discharge oil filter.
A method of filtering oil from a stream of compressed air generated from an air brake system includes positioning a discharge oil filter between a heat generating element and an air dryer. The discharge oil filter is positioned sufficiently close to the heat generating element to assure that entrained water in the compressed air is maintained in a vapor state during filtration.
The method of filtering oil from a stream of compressed air preferably includes agglomerating the oil in the discharge oil filter and removing the agglomerated oil downstream from the filter.
A primary benefit of the subject invention resides in minimizing oil contamination of a desiccant material located in an air dryer of a compressed air system.
Another benefit of the subject invention resides in the ability to effectively filter oil from a compressed air stream without having to use a complex drainage system or a separate heating element.
Still another benefit of the subject invention is the provision of an oil filter, the placement of which maintains water in a vapor form so that oil can be more easily filtered from the compressed air stream.
Still other features and benefits of the invention will become apparent to those skilled in the art upon reading and understanding the following detailed description.